Stones or Carbide for valve work?

[Newbomb Turk]

What did you use when you worked for Kevin for 2 days ? We have only stones.
( Not expecting a reply lol )

Awwwww...I had to use F'ing stones. I'm not into doing valve jobs with a stone and I can't think of an instance where I'd chose a stone over a carbide.

 

[Newbomb Turk]

Any time I've inspected and reassembled heads for customers that are ooth box carbide cut seats I've needed to lap in the valves. When I do my normal valve job with the stone I have found they seal much better. A cutter doesn't leave a uniform concentric seat , there is always a high spot and a low spot. That's what I have found.

That's because either the carbide is dull or the pilot is flexing. Something like that.

I forget if the A or the B carbide is the bigger one (IIRC it's the B carbide) but once you get to cutting with the full blade it puts a terrific load on the pilots and everything else and they will move around.

You also have to make sure the top of the pilot and the driver aren't ate up.

Of course, cutting BC seats and some of the nickel based seats is hell on pilots and stuff. You night skate by with HSS pilots but once you get up over about a 2.150 valve you really load the cutter and you need carbide pilots or the seat will never be round.

 

[MOPARMAGA]

That's because either the carbide is dull or the pilot is flexing. Something like that.

I forget if the A or the B carbide is the bigger one (IIRC it's the B carbide) but once you get to cutting with the full blade it puts a terrific load on the pilots and everything else and they will move around.

You also have to make sure the top of the pilot and the driver aren't ate up.

Of course, cutting BC seats and some of the nickel based seats is hell on pilots and stuff. You night skate by with HSS pilots but once you get up over about a 2.150 valve you really load the cutter and you need carbide pilots or the seat will never be round.

I'm pretty sure the seats on heads where people are getting paid to do it correctly are way better by a lot compared to a production line guy in some other country.